> Counterexamples welcome.

I mentioned "peas and honey" in another comment. zucchini and lube if you wanted to go for "haha weird sex practices", though just having condoms/lube in there doesn't make things intrinsically funny the way the OP seems to imagine. baby food and wine/headache pills/earplugs, for more sitcom-level humour ("haha, yeah, having a newborn is hard, we've all been there!"). knife and large garbage bags for a darker turn

the basic idea is "these two specific items suggest a funny image of them being used together, with the added context that it was likely just a random coincidence". it's not laugh-out-loud humour, but it can be amusing.

A few I’ve seen in person are someone buying about a dozen pallets of water and a half dozen of a vegetable (it was cabbage or leek if I recall). But that was more about the absurd looking quantity while only wanting just those two items. I assume most of the “funny orders” I see are restaurant owners who already got most of their items delivered, which makes them a large deviation from the expected family purchaser. This is something I have only seen at specific stores (similar to costco) in specific cities.

Some combinations could be funny, like a pregnancy test and something really mundane but odd like a whole pineapple and a large bag of lettuce

Counterexample: https://xkcd.com/236/